Catalyst For A Naphtha Reforming Process

ABSTRACT

The present disclosure relates to a catalyst for a naphtha reforming process. The catalyst comprises a chloride free zeolite coated alumina support impregnated with 0.01 wt % to 0.5 wt % active metal and 0.01 wt % to 0.5 wt % promoter metal, characterized in that the thickness of the zeolite coating on the alumina support ranges from 100 μm to 200 μm.

FIELD OF THE DISCLOSURE

The present disclosure relates to a catalyst for a naphtha reformingprocess.

DEFINITIONS

An active metal is a Group VIII metal of the modern periodic table. TheGroup VIII metals are platinum (Pt), palladium (Pd) and nickel (Ni).

A promoter metal is a Group IV metal of the modern periodic table. TheGroup IV metals are tin (Sn), rhenium (Re) and iridium (Ir).

ZSM-5 is an aluminosilicate zeolite belonging to the pentasil family ofzeolites and its chemical formula is Na_(n)Al_(n)Si_(96-n)O₁₉₂.16H₂O(0<n<27).

Mordenite is a zeolite mineral with the chemical formulaAl₂Si₁₀O₂₄.7H₂O.

Ultra-stable Y (USY) zeolite is a form of type Y zeolite with themajority of sodium ions removed and treated thermally to enhance itsthermal and steam stability.

H-beta zeolite is a high-silica content zeolite having full threedimensional 12-ring pore system.

MCM-22 is a type of zeolite having unique phase and good crystallinity.

ZSM-12 is a type of pentasil zeolite having silica to alumina ratioabove 33.

BACKGROUND

Catalytic naphtha reforming is an important industrial process. Duringthe naphtha reforming process, mainly low-octane straight chain alkanes(paraffins), with 6-10 carbon atoms, are reformed into molecules havingbranched alkanes (isoparaffins) and cyclic naphthenes, which are thenpartially dehydrogenated to produce high-octane aromatic hydrocarbonssuch as benzene, toluene and xylenes (BTX) in the reformate. The naphthafeedstock used for catalytic reforming contains naphthenic hydrocarbons,paraffinic hydrocarbons and aromatic hydrocarbons of different carbonnumbers. The major reactions in naphtha reforming process includedehydrogenation of naphthenes, dehydrocyclization of paraffins,isomerization of paraffins and hydrocracking. The chemical reactions inreforming process occur in presence of a catalyst and a high partialpressure of hydrogen. The catalysts used for reforming process areusually bifunctional in nature (i.e. having metal function and theacidic function). In a typical reforming process, naphtha is processedover the conventional acidic reforming catalysts where, one or moredehydrogenation metals, i.e. noble metals with stabilizing metal ionsare supported on chlorided Al₂O₃.These conventional reforming catalystscomprises platinum alone or along with Re, Ir, Sn or Ge as a promotermetals on gamma alumina support. However, it is observed that reformingof naphtha in the presence of conventional catalysts results inundesired products.

Further, the gamma alumina support of the conventional reformingcatalysts consists of corrosive and non-eco-friendly ingredients such aschloride that provides required acidity essential for the process.However, the activity of the conventional catalysts decreases due to theformation and accumulation of coke on the catalyst as well as bysintering of metals on the catalyst surface during the naphtha reformingprocess.

In the conventional reforming process, the C8 aromatic isomers formedi.e., ethyl benzene (EB), para-xylenes (p-X), meta-xylenes (m-X), andortho-xylenes (o-X) appear in thermodynamic equilibrium with theproduct. Generally, the ethyl benzene formed during the conventionalreforming takes an idle ride in the post reforming downstream p-xylenerecovery unit, thus occupying unit capacity and leading to undesiredoperating cost.

Therefore, there is a need of a catalyst which reduces the formation ofethylbenzene in the product. Further, there is a need of a catalyst thatovercomes the drawbacks associated with the conventional catalyst.

OBJECTS

Some of the objects of the present disclosure, which at least oneembodiment herein satisfies, are as follows:

It in an object of the present disclosure to provide a catalyst forreforming of naphtha.

It is another object of the present disclosure to provide a catalystwhich possesses dual functionality (i.e. the catalyst can be used forreforming as well as dealkylation).

It is yet another object of the present disclosure to provide a catalystwith optimum acidity for reforming reaction.

It is still another object of the present disclosure to provide acatalyst with reduce corrosive effects on process unit.

It is still another object of the present disclosure to provide anefficient and eco-friendly catalyst.

It is a further object of the present disclosure to ameliorate one ormore problems associated with the conventional catalysts or at leastprovide a useful alternative.

Other objects and advantages of the present disclosure will be moreapparent from the following description which is not intended to limitthe scope of the present disclosure.

SUMMARY

The present disclosure provides a catalyst for a naphtha reformingprocess. The catalyst comprises a chloride free zeolite coated aluminasupport impregnated with 0.01 wt % to 0.5 wt % active metal and 0.01 wt% to 0.5 wt % promoter metal, the thickness of the zeolite coating onthe chloride free alumina support ranges from 100 μm to 200 μm.

The zeolite is at least one selected from a group consisting of ZSM-5,mordenite, USY, H-Beta, MCM-22, and ZSM-12.

In accordance with the present disclosure, the zeolite is ZSM-5comprising SiO₂ and Al₂O₃ and the ratio of SiO₂ to Al₂O₃ in ZSM-5 is15:1.

The active metal is at least one selected from the group consisting ofplatinum (Pt), palladium (Pd) and nickel (Ni).

The promoter metal is at least one selected from the group consisting oftin (Sn), rhenium (Re) and Iridium (Ir).

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The disclosure will now be described with reference to the accompanyingnon-limiting drawings:

FIG. 1 illustrates the SEM micrograph of a catalyst in accordance withthe present disclosure; wherein the catalyst depicts the thickness ofthe zeolite coating of size 135 microns.

DETAILED DESCRIPTION

The present disclosure provides a catalyst for a naphtha reformingprocess. The catalyst of the present disclosure is used for reforming ofnaphtha.

In a first aspect, the present disclosure provides a catalyst thatcomprises of a chloride free zeolite coated alumina support impregnatedwith 0.01 wt % to 0.5 wt % active metal and 0.01 wt % to 0.5 wt %promoter metal. The thickness of the zeolite coating on the chloridefree alumina support ranges from 100 μm to 200 μm.

The zeolite is at least one selected from a group consisting of ZSM-5,mordenite, USY, H-Beta, MCM-22, and ZSM-12.

In accordance with one embodiment, the zeolite is ZSM-5 comprising SiO₂and Al₂O₃.

In accordance with one embodiment, the ratio of SiO₂ to Al₂O₃ in ZSM-5ranges from 10:1 to 20:1.

In accordance with another embodiment, the ratio of SiO₂ to Al₂O₃ inZSM-5 is 15:1.

Examples of the active metals impregnated in the catalyst includeplatinum (Pt), palladium (Pd) and nickel (Ni).

In accordance with one embodiment, the active metal impregnated in thecatalyst is platinum (Pt).

In accordance with another embodiment, the concentration of the platinum(Pt) ranges from 0.01 wt % to 0.75 wt %.

Examples of the promoter metals impregnated in the catalyst include tin(Sn), rhenium (Re) and Iridium (Ir).

In accordance with one embodiment, the metal impregnated in the catalystis tin (Sn).

In accordance with another embodiment, the concentration of the tin (Sn)ranges from 0.01 wt % to 0.75 wt %.

The alumina support of the conventional catalyst contains chloride whichmakes the catalyst highly acidic. Due to this, undesired C₁ to C₄gaseous products are formed by cracking reaction during the reformingprocess.

The catalyst of the present disclosure comprises a chloride free aluminasupport coated with the zeolite and impregnated with 0.01 wt % to 0.5 wt% active metal and 0.01 wt % to 0.5 wt % promoter metal, which providesoptimum acidity to the catalyst resulting into lower cracking during thereforming process. This leads in the reduction in formation andaccumulation of coke on the catalyst surface, and sintering of metals onthe catalyst surface during the reforming process. Due to this, theselectivity and the yield of desired hydrocarbons including desiredaromatic compounds are improved.

The present disclosure is further illustrated herein below with the helpof the following examples. The examples used herein are intended merelyto facilitate an understanding of the ways in which the embodimentsherein may be practiced and to further enable those of skilled in theart to practice the embodiments herein. Accordingly, the examples shouldnot be construed as limiting the scope of the embodiments herein.

The catalyst of the present disclosure comprises a chloride free zeolitecoated alumina support impregnated with 0.01 wt % to 0.5 wt % activemetal and 0.01 wt % to 0.5 wt % promoter metal. The thickness of thezeolite coating on the chloride free alumina support is illustrated inthe following example:

EXAMPLE

FIG. 1 illustrates the SEM micrograph of a catalyst in accordance withthe present disclosure; wherein the catalyst depicts the thickness ofthe zeolite coating of size 135 microns.

The catalyst of the present disclosure described herein above shows thatit overcomes the problems faced by the conventional catalyst.

Technical Advancement

The present disclosure relates to the catalyst. The catalyst has severaltechnical advancements:

-   -   the alumina support of the catalyst does not contain chloride;    -   the catalyst has optimum acidity due to presence of chlorine        free zeolite layer on the catalyst surface which results into        less chain cracking and reduced coke formation during the        reforming process.    -   the selectivity of desired hydrocarbons is improved; and    -   the yield of desired aromatic compounds is improved.

Throughout this specification the word “comprise”, or variations such as“comprises” or “comprising”, will be understood to imply the inclusionof a stated element, integer or step, or group of elements, integers orsteps, but not the exclusion of any other element, integer or step, orgroup of elements, integers or steps.

The use of the expression “at least” or “at least one” suggests the useof one or more elements or ingredients or quantities, as the use may bein the embodiment of the invention to achieve one or more of the desiredobjects or results. While certain embodiments of the inventions havebeen described, these embodiments have been presented by way of exampleonly, and are not intended to limit the scope of the inventions.Variations or modifications to the formulation of this invention, withinthe scope of the invention, may occur to those skilled in the art uponreviewing the disclosure herein. Such variations or modifications arewell within the spirit of this invention.

The numerical values given for various physical parameters, dimensionsand quantities are only approximate values and it is envisaged that thevalues higher than the numerical value assigned to the physicalparameters, dimensions and quantities fall within the scope of theinvention unless there is a statement in the specification to thecontrary.

1. A catalyst comprising a chloride free zeolite coated alumina supportimpregnated with 0.01 wt % to 0.5 wt % active metal and 0.01 wt % to 0.5wt % promoter metal, wherein the thickness of said zeolite coating onsaid chloride free alumina support ranges from 100 μm to 200 μm.
 2. Thecatalyst as claimed in claim 1, wherein said zeolite is at least oneselected from a group consisting of ZSM-5, mordenite, USY, H-Beta,MCM-22, and ZSM-12.
 3. The catalyst as claimed in claim 1, wherein saidzeolite is ZSM-5 comprising SiO₂ and Al₂O₃.
 4. The catalyst as claimedin claim 3, wherein said zeolite is ZSM-5 having the ratio of SiO₂ toAl₂O₃ ranging from 10:1 to 20:1, preferably 15:1.
 5. The catalyst asclaimed in claim 1, wherein said active metal is at least one selectedfrom the group consisting of platinum (Pt), palladium (Pd) and nickel(Ni).
 6. The catalyst as claimed in claim 1, wherein said active metalis platinum (Pt).
 7. The catalyst as claimed in claim 1, wherein saidpromoter metal is at least one selected from the group consisting of tin(Sn), rhenium (Re) and Iridium (Ir).
 8. The catalyst as claimed in claim1, wherein said promoter metal is tin (Sn).